Remote control for radioreceivers



NOV. 6, 1934, VREELAND 1,979,588

REMOTE CONTROL FOR RADIORECEIVERS Filed July 24) 1929 2 Sheetsl-Sheet 1 I NVENTOR &

Nov. 6, 1934.. 'F[ K. VREELAND ,9

- REMOTE CONTROLFOR RADIORECEIVERS I Filed July 24, 1929 2 Sheets-Sheet 2 RF-I RF'E DE AF-l A52 Patented Nov. 6, 1934 UNITED STATES PATENT OFFICE Frederick K. Vreeland, Montclair, N. J.

Application July 24, 1929, Serial No. 380,515

2 Claims.

The invention herein described is a remote control system for radio receivers.

The object of the invention is to control the station or frequency selection and other operating features of a radio receiver from a point or points located at a distance from such receiver.

A further object of the invention is to simplify the process of control by making the usual selector dial unnecessary, and still further to simin plify the process by substituting automatic features for manual adjustments. In the fullest embodiment of the invention the operation of the receiver may be reduced to the single act of pressing a button, the selecting of the station by the adjusting of the receiver to the proper signal frequency and the governing of the output level being accomplished automatically.

Other features of the invention include means whereby the receiver may be controlled from any one of several different points, and the output of the receiver heard at any one or anygroup of such points, and means for preventing confusion or conflicting operation which might result from the several operators working at cross purposes.

In carrying out the present invention I preferably employ, in certain embodiments of the invention, features that are disclosed in my patents No. 1,666,518, April 17, 1928, No. 1,682,874, September 4, 1928, No. 1,725,433, August 20, 1929, and No. 1,730,987, October 8, 1929 and applications Serial Nos. 300,172' and 377,409 relating to radio receivers having a band reception characteristic, also certain features of my application Serial No. 297,337 relating -to automatic governors for electrical amplifiers. These features are highly desirable when combined with the other elements of my remote control system. The automatic governor permits the operation of a key or push button control for selecting stations whose signal strengths differ over a wide range, maintaining the output at-a predetermined level without manual adjustment, irrespective of the input signal strength. The band reception feature is also valuable, not only because of the fidelity of tone that it achieves together with high selectivity, but also because the band characteristic, if the reception band is made a little wider than the transmission band,

permits some tolerance in the operation of the remote control mechanism without distortion or weakening of the signal, thus avoiding the necessity of great mechanical precision in the mechanism.- These latter results are impossible when a sharply tuned receiver is employed.

In the drawings Figure 1 shows schematically a typical embodiment of the invention.

Figures 2 and 3 show details of a typical construction of the automatic selector mechanism.

Figure 4 shows a typical construction of one of the remote control units.

Figure 5 is a schematic view showing one form of a band receiver.

In the operation of a radio broadcast receiver it is usual to operate the frequency selector by the rotation of a shaft or member which actuates variable circuit elements which in turn perform the frequency selection. This shaft or frequency selector member is ordinarily operated by a knob or other manual control. It is also usual to control the output level for each individual station by a volume control, also manually operated. It is usual furthermore to turn the electrical power on or on? by a manually operated switch located at the receiver. When the present invention is employed all of these manual operations atthe receiver are made unnecessary so that the receiver may be located in any convenient or even relatively inaccessible place. In the preferred embodiment of the invention any or,a1l of these operations are performed automatically, but under the control of an operator or operators at one or more remote points.

The frequency selector is operated preferably by an electric motor or other prime mover, and the selection of the desired station or signal frequency is controlled, in one embodiment of the invention, by the operation of a master dial, which causes synchronousor otherwise corresponding motion of the frequency selector member'of the receiver, thus making it possible to adjust the receiver at will for the reception of any wave frequency within its range. In another embodiment, the operation is still further simplified by pressing a button or key corresponding to any desired signal frequency, thus setting in operation an automatic selector which adjusts the receiver for the selection of the desired frequency. Another feature of the invention is a very simple device for setting the various station selectors so that each will select any desired frequency.

In the preferred embodiment, when the desired signal frequency is selected the output level of the signal is automatically governed and maintained at a predetermined value, irrespective of the input signal strength, and the strength of the output signal may be altered at will by an output control or attenuator located at -the control point. The output signal strength at any or all of the several control points may be independently adjusted, and when so adjusted the desired output level will be automatically maintained at each of such points irrespective of the input signal strength.

In Fig: 1, which represents a. convenient arrangement embodying these various features, 1 and 2 represent two typical control units, each 3 associated with its own loud speaker Y, through radio receiver, which isshown in diagrammatic particular receiver construction,

beomitted or modified, but. they are'all desirable for securing the fullest advantages of the invention.

In the receiver 3, S indicates the shaft or se- -lector member which controls condensers or other variable circuit elements for frequency selection. The electrical selective system, controlled by this element, is preferably one having a band response characteristic, and may include a band selector or a spaced band amplifier or both, as set forth in my patents and applications above mentioned. Q is a dial or equiva-r lent frequency indicating device of any suitable form which may be used for observing the setting of the frequency selector. This setting may be performed manually by means of the control knob N, as an alternative to the remote control operation. The shaft or spindle S of the control knob N. is connected by a worm or other suitable gearing W to a motor M whereby the automatic or remote operation of the selector is effected. The shaft S is preferably connected to the gearing-W by a couplifig that permits independent motion of the shaft and gearing, such as a slip connection w, so that the manual control N may be operated without rotating the motor and gearing. The device,Q is shown as I connected to the shaft S by a belt and pulleys.

The operation of the motor M is controlled by theautomatic selector mechanism 4, through one or the other of two interconnected remote control devices, one being a master dial control which functions through the continuously acting,

element V1, and the other a button or key control which functions through the operation of the individual selector positioning elements D with their associated parts. Either or both of these control mechanisms may be embodied in the apparatus as desired.

The key controlmechanism comprises a plurality of selector positioning elements here shown and their associated parts is shown in the detail drawings, Figs. 2 and 3. The discs D are made each with a contact'sector, here shown as a semi-circular peripheral portion of larger diameter, the remaining semi-circular part being It will be understood that certain of these features may any desired construction as will be readily a diameter of the disc D. These contact brushes are so arranged that when the disc D is in the position shown neither of them makes contact with the disc, but if the disc is rotated by the smallest amount, one or the other brush will make contact with the contact sector, depending on the direction of the rotation. All of the brushes C are connected to one-terminal of the motor M and all of the brushes CC are 'connectedto a. second terminal of the motor M. These terminals are so arranged that when a current is sent through one of them, say that connected to the brush C, the motor operates in a clockwise direction and when'current is sent through the other terminal, say that connected to the brush CC, the motor rotates in a counterclockwise direction. This reversing operation of the motor may be accomplishedin any desired manner. For example: when a series commutator motor is. used it may be provided with two field windings, wound .or connected in opposite senses, one field winding con-- nected to the brush C and the other to the brush CC. Changing contact from one brush to the other will cause a reversal of the motor field. and so reverse the direction of rotation. If an induction motor is employed, the two terminals maybe connected to separate stator windings causing opposite rotations, employing understood.

The selector positioning elements D are insulated from each other, and each has associated with it a separate contact brush A, whereby current is admitted to the particular element desired. The element thus energized will supply "current through the corresponding brush C or CC, if either is making contact, causing'the motor to operate and rotate. the shaft S. The connections are so chosen-that,in either case the motor will drive the shaft in such a direc-' tion as to bring the element D into the position shown in Fig. 2, when both the brushes C and CC will break contact and the mechanism stops. The ,position in which the "mechanism stops depends upon the angular position of theelement D with respect to the shaft S. The I angular positions of the several elements may be predetermined and fixed to correspond to certain desired signal frequencies, but preferably the elements are arranged to rotate on the shaft so that they may be adjusted at will. In the particular preferred construction shown in Fig." 3, the several discs or elements D are rotatably mounted on a hub H of insulating material 138 which is fixed to the shaft S. The elements D are separated by insulating spacers R which drive the elements by friction. The spacers R are held in a fixed angular position on the hub by keys or pins. K, which however permit a certain small longitudinal movement to distribute the pressure uniformly among the elements. Uniformity of pressure is secured by spring By means of this non-rigidconne'ction any 140 A setting finger F is spring ergize the key bus L. energized only by closing the switch in its own is opposite the point of the finger F. The spring pressure exerted by the button P when pressed by the operator then causes the finger to enter the notch X where it rests on the insulating insert I, holding the element D'in the position shown without making electrical contact therewith. The insert I is not essential, since the brushes C and CC alone will open the circuit,

but it is desirable in case of inaccurate alignment of the parts. When the disc is thus held in fixed position the shaft S may be rotated manually by the knob N and the receiver tuned to any desired signal frequency in the ordinary way. When thus tuned the button P is released and. the corresponding selector element D remains in the position in which it is set. Thereafter the element D, when energized through the contact spring A, will operate the mechanism to bring the selector to the frequency corresponding to the position in which the disc is set.

This setting may be accomplished for each of the several elements D by operating the corresponding button P. Each disc may thus be set for a different signal frequency and when so nec'ts the corresponding spring A and element D with the key bus L. If the key bus L and the line bus L are energized the mechanism will be set in operation to bring the frequency selector to the position determined by the particular key a, b, c, d, e that is closed.-

The line bus L may be energized by closing any one of the switches M1, M2 or M3, the first two switches being located in the control units 1 and .2, andthe'third switch M: being located at-the receiver 3. The switches M1 and M: are preferably made with two contact points, as shown; the second contact point serving to en- The key bus L is thus control unit, a's'Mi. If any one or more of the switches M1, M2 or M3 is closed, the line bus L will be energized, thereby applying power to the receiver 3, and the motor If either of the switches Mi or M: is closed, the corresponding key bus L' will also be energized so that any desired one of the selector keys a, b, c, d, e, in the same control unit may be operated, setting the frequency control mechanism in operation.

' The keys in the other control unit or units will not then be operative. When rotation of the selector shaft ceases the receiver will then .be responsive to the signal frequencycorresponding to the key that is closed.

The output. of the receiver 3 is delivered through terminals 0 to one or more of the sound projectors-or loud speakers YY operated by the receiver. Each of these loud speakers is preferably controlled by an attenuator At, whereby the loudness of the sound may be adjusted, and a switch whereby the speaker may be turned on or ofi.

In circuit between the output terminals 0 and the speakers YY is an output control relay OR which, when it operates, opens the circuit and disconnects the speakers from the receiver. The operation of this relay is controlled by the selector mechanism. In the arrangement shown the relay has two windings which are connected respectively to the two sides of the motor control circuit as shown, so that whenever the mechanism energizes the motor to operate the frequency selector the loud speakers will be disconnected and will remain disconnected until the frequency selection is complete and the mechanism stops. The loud speaker or speakers will then operate on the selected signal. Unde- -sired signal or local noises during the operation tomatically regulates the over-all gain of the receiver. It operates to maintain the output level of the signals delivered by the receiver at substantially the desired value, irrespective of the input signal strength. The form of governor shown is of the type set forth in my co-pending application 297,337 filed Aug. 3, 1928, comprising a rectifier R, which derives an electromotive force from the output terminals 0 through the adjusting potentiometer p and transformer T1, which it rectifies thereby setting up a floating charge in the condenser C, which floating charge impresses an electromotive force on the grid of a regulator tube B inserted in the plate circuit of the amplifier of the receiver 3. The floating charge in the condenser C, which depends upon the output level of the signal and on the setting of the potentiometer p, thus impresses a greater or less negative potential on the grid of the regulator tube 13 and thus regu-' lates the power supply and hence the gain of the amplifier. R2 is a series resistor for regulating the speed of response of the governor, and R1 is a shunted resistor or leak for regulating the speed of recovery. By means of the governor 5 the output level of the signal delivered by the receiver 3 is maintained substantially constant irrespective of the input signal strength, this level being determined by the setting of the potentiometer p.

It will be readily understood that any number of control units similar to that shown at 1 may be employed. A second control unit is shown at 2, its various circuits being shown connected in parallel with the circuits of control unit 1. a

To avoid confusion or conflict in the operation of two or more control units, pilot lights I and I are employed to indicate the condition of the apparatus. When the power is turned on by the closing of any one of the line switches M1, M2 or M3 the line pilot light I is illuminated in each of the control units. If the selector has been operated by the closing of any one of the selector keys a, he, d; e, the light corresponding to the key closed is illuminated in each of the conavoiding conflicting operation of the selector keys. Preferably the selector keys are interlocked with each other and with the line switch, as will'now be explained.

A convenient construction of the interlocking mechanism is shown in detail in Fig. 4. a, b, c, d, e, are the selector keys, corresponding to the parts so marked in Fig. 1. Each selector key is provided with a cam latch 6, cooperating with an interlocking member '7 having a restoring spring 8, which holds, it in position to engage the cam latches 6. When any key is depressed its latch 6' engages the interlocking member '7, which'holds the key in the closed position.

The closing of the key-operates the contact springs 9 to close the selector circuit connected to one of the brushes A ofFig. 1. When another key ,is depressed its cam latch, engaging the interlocking member, moves it against the spring pressure, so that the first cam is released and opens the circuit of its contact spring 9. The second key is then held in closed position as before, and it remains closed until released by the interlocking member.

The interlocking member 7 has a connection with the line switch M1 which operates to push the interlocking member against the spring 8 when the line switch M1 is open. The opening of the line switch thus releases any selector key that may be closed, clearing all the selector circuits. The circuits are thus in condition for being operated by any other control unit, such as 2, when the line switch M2 is closed. When the line switch is open the selector keys are not energized nor will they remain closed. The

opening of the line switch, releasing the interlocking member, extinguishes all the pilot lights, showing that the lines are clear for the opera tion of any desired control unit.

The arrangement shown in Fig. 1 includes, in addition to the. key controlled frequency selector units fo'r setting the apparatus for any predetermined frequency, a remote dial control,

whereby the selector may be adjusted at will forany desired frequency within its range by operating the remote control dial V2 shown in the control unit 2. Control dial V2 operates a voltage divider, excited by a source of electromotive force E. A similar and preferably equal voltage a divider V1 is operated by the selector shaft S of the receiver 3 and is excited also by the source of electromotive force E. When the two voltagedividers V1 and V2 are set in corresponding positions there will be no potential difference between their respective contact' arms. But if ment of V2 with respect to V1 is in one direction the potential difference will be positive and one of the relays, say PR1, will operate. If the displacement of V2 is in the opposite direction the potential difference will be negative and. the

- other polarized relay PR2 will function. The

functioning of either relay preferablyoperates a second relay'CR1 or CR2 of more rugged construction, vwhich in ,turn, closes a contact con- *nected to .oneof the brushes C or CC of the selector mechanism. The use of the second relays CR1 and CR2 is desirable to handle the relatively largecurrent required to operate the motor M while permitting a. very sensitive construction 'of'the polarized relays PR1 and PR2,

so that the system will respond to a very-small relative displacement of the voltage dividers V2 and V1. Any such displacement in either direction will set in operation one set of relays PR1, CR1 or PR2, CR2, depending on the direction of the displacement and this will close one of the motor control circuits C or CO, the connections being so chosen that the resulting rotation of the motor Mand shaft S will bring the voltage divider V1 into the position corresponding to that of V2. When this position is reached the potential difference becomes zero, the relays release and the motor stops. An additional contact key I is preferably employed in control unit 2, so that the remote dial control may be thrown on or off by the operation of this key, any other I key being simultaneously opened by the interlocking mechanism.

It will thus be seen that when the key ,2 is closed, any motion of the dial voltage divider V2 will cause a motion of the frequency selector mechanism in a direction corresponding to that of the voltage divider V2 and this motion continues until the voltage divider V1 comes into the position corresponding to that of V2. Thus .the selector may be turned at will in either direction and by any desired amount by theoperation of the remote control dial V2 and the selector may thus be set for any desired fre-,, quency. Only one remote selector dial V2 is shown in the drawings, but it will be readily understood that'any number of such control dials may be employed, either in conjunction with key selectors as shown, or as independent dial selector units, as may be desired.

. It will be seen from the above description that the arrangement of Fig. 1 provides for complete control of all the functions of. a radio re ceiver from one or more distant points, whether by the operation of keys for selecting predetermined frequencies or by the arbitrary selection of any desired frequency, provides means for governing automatically the output level of the received signals irrespective of the input signal strength, and provides also means for determining the magnitudes of the output levels atthe several receiving points independently, so that a signal may be received at any one or any group of such points, each with its own desired output strength, such output strength being determined at will at the corresponding remote control point. It includes also means for interlocking the several control circuits to prevent conflicting operation, and provides at'each'control point pilot -tor, a motor operating such frequency selector,

means located at a distance for initiating the operation of the motor, and means in operative relation with the selector for determining the direction and extent of the operation of the selector,.said means including a selector positioning element opeartively connected to" the selector,

electricalconnections co-operating with the selector positioning element tov control the operation of the motor, and mean for holding the selector positioning element in. neutral position.

while the frequency selector is moved with respect to the selector positioning element, and the selector positioning element is set to correspond to any desired signal frequency.

2. A remote control apparatus for electrical receivers wherein are combined a frequency selector, a motor operating the selector, a plurality of selector positioning elements operatively connected to the selector, a pair of electrical contacts having a common terminal and two free terminals operated by each selector positioning element, a common connection from onefree terminal of all the pairs, a second common connection from the other free terminal of all the pairs, connections from the two common connections to'the motor causing, when energized, rotation in opposite directions, electrical 

